I installed the WPBB forum after trying another which was far too confusing and didn't fit seamlessly within my website.

The WPBB plugin has been easy to setup. There have been a few tweeks so far to get it working as required, but nothing major and so far everything I have wanted to achieve has been relatively easy to solve.

This plugin is REALLY easy to set-up and start using, by far the best I have tested.
The only missing piece of information being that, when using WP multisite, you must create all your settings within the main site's dashboard; this cannot be done in the DB of a sub-site.
Other than that, it is up and going within 10 minutes... and I am no techie !
Good job !